This invention relates to a process using electrogenerated bases as catalysts for the alkylation of nitrogen acids.
In U.S. Pat. No. 4,132,611, Baizer et al, there is described the use of electrogenerated bases as catalysts for the addition of organic electrophiles to carbon acids, and certain other related prior art is described therein. One of the reactions described in this patent is alkylation of the carbon acid and this is described broadly in column 3, lines 15-27 of the patent.
Nitrogen acids of the type described herein have been previously N-alkylated under basic conditions using a variety of strong bases, e.g., sodium in liquid ammonia or sodium hydride, potassium t-butoxide, etc., in suitable product solvent (J. Zabicky, "The Chemistry of Amides," Interscience Publishers, New York, 1970). The reactions are usually carried out sequentially by adding the base to the nitrogen acid to form the anion and subsequently introducing the alkylating agent.
Although alkali hydroxides have been used to generate nitrogen anions from nitrogen acids under very special conditions, the strong bases having general applicability suffer from the well-recognized disadvantages of cost, safety, ease of handling, waste disposal, or a combinations of these.
The present invention involves the N-alkylation of the described nitrogen acids under anion-forming conditions by the electrochemical generation of strong bases from suitable probases having the advantage that the protonated electrogenerated base may be easily converted to the original probase with the liberation of protons making the alkylation process catalytic in probase and stoichiometric only in electricity. In the preferred embodiment of the invention, the probase is regenerated in situ by anodic oxidation of the protonated electrogenerated base, either directly or indirectly, in an undivided electrochemical cell containing a proton scavenger. Indirect anodic oxidation of the protonated electrogenerated base to probase can be, e.g., with anodically generated halogen.